1. Field of Invention
The invention relates to an apparatus and a system of operation of a plurality of ion-exchange membranes. More specifically, the invention relates to an apparatus and system of operation of a plurality of electrodialysis membranes and gaskets stacked for separation of components from liquids passing through the membranes.
2. Description of the Related Art
Prior methods of treatment for separating polar components in liquid mixtures having contaminants have been utilized to purify water, to desalinate water, and to purify ethylene glycol or other mixtures of chemicals. One method utilizes ion exchange resins for separation of polar components on granular ion exchange resins, which require chemical regeneration of the resins and/or disposal of the resins. Another treatment method for separating polar components in liquid mixtures include micro-porous membranes which selectively allow smaller polar compounds to pass through the membrane, while denying passage of larger sized polar compounds. Another treatment method includes ion exchange membranes having anion and cation exchange membranes assembled in an alternating configuration in a unit of membranes.
Prior purifying and recycling devices include a plurality of ion exchange bipolar membranes separating solution compartments, and gasket separators secured together in face-to-face contact in a configuration of a multi-layered, stacked plate. The gasket separators between the membranes provide sealing at the edges of the stacked plate of membranes, and enable a fluid to flow into and out of the stacked plate and through the individual solution compartments between the stacked plate of membranes. The ion exchange bipolar membranes can contain an anode and a cathode electrode at the respective ends of the stack of membranes in order to provide an electrical input for maintaining a differential voltage between the anode end and the cathode end. When a direct current is passed through the multi-layered stacked plate, the ions contained in the solution to be purified will migrate in a direction in relation to the current depending on the charge of each ion in the solution. The cations move toward the cathode or negative electrode, while the anions move toward the anode or positive electrode. By controlling the electrical input, and therefore the differential voltages, an operator induces the movement of the cations and anions in different directions across the stack of membranes, thereby operating the purifying and recycling system to remove contaminants from ethylene glycol, water, and/or other liquid solutions.
At least three types and sizes of stacks of electrodialysis membrane units are utilized in prior purifying and recycling devices, including an electrodialysis concentration cell having a cation membrane, a dilution or feed compartment, an anion membrane, and a concentrate or product compartment which forms a unit utilized for desalinating of brine solutions. A second type of electrodialysis membrane unit includes a two-compartment cation cell having a bipolar membrane, a feed compartment, a cation membrane, and a base or product compartment. A third type of electrodialysis membrane unit includes a two-compartment anion cell having a bipolar membrane, a product compartment, an anion membrane, and a feed compartment. Additional types of electrodialysis membranes can include any combination of layers of the above three types to form a plurality of cation and anion membranes, interspersed with compartments and gaskets separating the compartments. Electrodialysis designs for flow through the stacks of electrodialysis membranes include sheet flow and tortuous flow. Sheet flow stacks induce liquid flow across the length or width of the active membrane surface area, and generally are utilized for low linear velocity conditions in the range of 5 to 10 cm/sec. Tortuous flow stacks induce liquids to take a long flow path around gaskets, and are utilized for higher linear flow velocity conditions in the range of 30 to 50 cm/sec.
Utilization of the electrodialysis designs as described above in stacks of membranes for purifying and recycling of ethylene glycol solutions, or for purifying water and desalinating water require a plurality of multiple membranes having complicated configurations. There is a need for a simplified design of a series of electrodialysis membranes in stacked configurations for improved removal efficiencies of contaminants in a purification and deionizing system.
Therefore, it is an object of the present invention to provide an improved membrane cell stack for purification of liquid mixtures.
It is another object of the present invention to provide a method of operation for an electrodialysis treatment system providing increased efficiency for ion-removal of liquid mixtures.
It is another object of the present invention to provide a membrane and gasket cell stack system having reduced assembly time.
It is another object of the present invention to provide a system having a plurality of membranes and interchangeable gaskets for improved efficiency for removal of contaminants by electrodialysis deionizing of liquid mixtures.
It is another object of the present invention to provide an improved system having a plurality of membranes and interchangeable gaskets for improved efficiency for deionizing liquid mixtures by an electrodialysis apparatus.
An apparatus and system of operation is disclosed for the separation of polar components, inorganic contaminants, and organic contaminants within liquid mixtures. The apparatus and system of operation for purification and deionizing liquid mixtures includes an operation of pretreatment by utilizing filtration for removal of inorganic contaminants and organic contaminants utilizing oil/water separation methods and settling methods for removal of suspended solids. The system of operation includes an operation of adsorption treatment for the filtrate effluent of the pretreatment operation. The adsorption operation includes removing organic contaminants by utilizing activated carbon adsorption methods.
The system of operation further includes an operation of deionizing for treating of the effluent liquids from the adsorption operation. The deionizing operation includes a system utilizing an apparatus having an electrodialysis cell stack including a plurality of disparate layers being stacked together, the electrodialysis cell stack having a first end and a second end, with the plurality of disparate layers stacked contiguous between the first end and second end. A support frame supports the cell stack and encloses a perimeter of the plurality of disparate layers, with the layers being disposed in a repetitive sequence of layers between the first outer end and second outer end of the support frame. The plurality of disparate layers of materials are disposed contiguous, having a first outer layer at the first end, and a second outer layer at the second end, with the plurality of disparate layers interdisposed therebetween. The plurality of disparate layers include at least two electrodialysis gaskets, the first of the electrodialysis gaskets being positioned as the first outer layer at the first end, opposite the second of the electrodialysis gaskets being positioned as the second outer layer at the second end.
A cathode electrode plate is positioned proximate to the first end and interior of the first electrodialysis gasket. An anode electrode plate is positioned proximate to the second end and interior of the second electrodialysis gasket at the second end. A voltage generating means is connected to the cell stack for application of an electrical voltage differential between the cathode electrode plate and the anode electrode plate.
The plurality of disparate layers are disposed between the cathode and anode electrode plates and include a series of layers of differing permeability, the layers selected from a group comprising a first electrodialysis membrane gasket, a first turbulence promoter, an anion membrane, a second electrodialysis membrane gasket, a second turbulence promoter, a cation membrane, a third electrodialysis membrane gasket, and a third turbulence promoter, whereby the plurality of disparate layers can be repeated in series as required. A connecting means provides connection of the plurality of disparate layers within the support frame, the connecting means including removably attachable connectors to allow the plurality of disparate layers to be replaced, and/or additional series of layers of differing permeability to be added to the electrodialysis cell stack.
The electrodialysis cell stack can further include the series of layers being repeated as required for removal of polar components and/or additional contaminants, with additional turbulence promoters being added to increase the dispersion of the liquid mixtures therethrough to increase the efficiency of removal of contaminants upon application of electrical voltage differential between the cathode electrode plate and the anode electrode plate.
The electrodialysis cell stack of disparate layers and enclosing frame of the deionizing operation provides continuous purifying of ethylene glycol and glycol/water mixtures, provides for continuous desalinating of water, and/or provides for continuous deionizing of water to generate ultra-pure water or other purified liquid mixtures.
The deionizing operation can be followed by an evaporation system for removal of excess water from the purified ethylene glycol or other liquid mixtures, with the purified liquids and/or deionized liquids being available for recycle and reuse. The combination of treatment operations and the deionizing operation provides a continuous operating system with minimized down-time and improved efficiencies over prior methods for purification and deionizing liquid mixtures.